Monday, January 21, is the third anniversary of Citizens United, the Supreme Court ruling that allows unlimited contributions to super PACs and other outside groups. Campaign finance reformers have been trying to chip away at the Citizens United ruling. New York State's attorney general has just introduced new rules to force some groups to reveal their donors.

Some outside groups, like super PACs, do have to disclose their donors. But other, nonprofit organizations never have to say where they got their campaign cash. It's become known as dark money. Millions of it poured into the 2012 election. New York Attorney General Eric Schneiderman is proposing new rules to shine some light on the dark money. Any nonprofit spending at least $10,000 on a campaign in New York would have to list its donors. Schneiderman says it could be a long list.

"New York is a place where people raise a lot of money and that gives us jurisdiction over a lot of these shadowy nonprofits," says Schneiderman.

New York is the first state to propose such strict new rules. Supporters of campaign finance reform hope it won't be the last.

"What I'm hoping for is that the actions by the New York state attorney general will serve as a model for other states coming out with their own transparency proposals," says Craig Holman, money and politics lobbyist for Public Citizen.

New York plans to finalize its rules in time for local elections in the fall.